Proper Air Conditioner Wiring

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Old 06-02-09, 08:28 PM
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Proper Air Conditioner Wiring

Hello. I recently bought a house with a Lennox AC unit and need to re-wire it up. I am by no means an electrician or an Air Conditioner repairman, but I am deft with my hands and a willing learner (and also very willing to save a few bucks).


THE UNIT:
Lennox 10acc-060-230-04
Nominal Voltage 208/230 1 phase 60 hz (min 197 max 253)
RLA 26.6
LRA 170
Fan Motor FLA 1.9 HP 1/3
Min Ckt Ampacity 35.2
Max fuse / Ckt Bkr (HACR) per NEC fusable/coupe circuit 60

WHAT IS THERE NOW:
60amp double breaker; Type SE Cable Style U THHN or THWN CDRS 3 CDRS #8 CU 600 VOLTS E73061 <UL> ( 8-2 Cu SE cable, I am guessing); 60amp non-fusible disconnect box (broken); three #8 CU THHN wires from the disconnect box to the AC unit (wires are charred inside the disconnect box, needs replacement)

THE AC REPAIRMAN RECOMMENDED:
60amp double breaker (leave as is)
New 6-2 Cu Romex
New 60amp fusible disconnect box
New time-delay fuses
and quoted an arm and a leg for his services


I feel this is a very doable job, but am simply not entirely sure of the materials needed to ensure my house does not give into involuntary pyrotechnics in future days to come. Any recommendation or insight on wire size, disconnect box type, size, and whether the fuses are really needed and how they work, would be greatly appreciated. Thank you very much.

P.S. The electric panel is about 55 feet from my AC unit; the basement is unfinished.
 
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Old 06-02-09, 09:23 PM
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well, I do not see any need for the fuses (and the fusible disco). A non-fused disco would be fine. Not sure why he would put in a fusible disco with the same size fuses as the breaker. It does not provide any real benefit.

I think you have more of a problem than what you need to replace. You should not have had any problems with the #8 you had but going to #6 won;t hurt. You either have a high draw problem with the unit or somebody did not install well and the terminals were loose, which will cause heat and burn the wires.

Where are you talking about running the 6-2 romex? You cannot run it outside. You need to run a flex conduit and individual conductors from the disco to the AC condenser.

from the disco to the panel would be fine as long as it enters the disco from the back (through the wall) so it is not exposed outside.
 
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Old 06-03-09, 09:23 AM
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Originally Posted by Penguin9 View Post
WHAT IS THERE NOW:
60amp double breaker; Type SE Cable Style U THHN or THWN CDRS 3 CDRS #8 CU 600 VOLTS E73061 <UL> ( 8-2 Cu SE cable, I am guessing); 60amp non-fusible disconnect box (broken); three #8 CU THHN wires from the disconnect box to the AC unit (wires are charred inside the disconnect box, needs replacement)
All of this is appropriate for the unit specified. Repair or replacement of the charred components should be just fine. With an unfinished basement, you should be able to go just a couple feet inside with a junction box so you only need to replace the last 5' or so of damaged wire to the outside.

Are there environmental issues that might have caused corrosion in the disconnect box like driving rain or spray from an irrigation system?

It's also possible the terminals just weren't installed tight. Add some NO-OX grease to the terminals as an insurance policy against future corrosion of the new wires.

THE AC REPAIRMAN RECOMMENDED:
60amp double breaker (leave as is)
New 6-2 Cu Romex
New 60amp fusible disconnect box
New time-delay fuses
All of this is overkill.
 
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Old 06-03-09, 08:20 PM
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A fusible disconnect might be required. Check the nameplate. If it says "Max Fuse Size" and not "Max fuse or breaker" size a fuse is needed in the circuit.

Otherwise a simple pullout disconnect would be sufficient.
 
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Old 06-03-09, 10:36 PM
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Nap and Ibpooks, you are both correct: I found the wires that connected to the AC terminal were trimmed down to 3 strands as opposed to the normal 6/7 required to make the connection.

All the charring occurred at the disconnect box, where the pullout disconnect was melted shut (we pulled the switch out and broke the inner cover), and the wires connected at the disconnect terminals were charred, with some light green deposit. This is what it looks like:


I don't know if linking pictures is considered breaking the rules, if I have broken the rules, I can promptly remove this link. I felt this picture would help visualize things a little better.

Pcboss, it does say "Max Fuse Or Circuit Breaker"; and per Nap and Ibpook's recommendation, looks like fuses do seem unnecessary.

QUESTION
For the connection from the new disconnect box to the AC unit, I understand I will need 2 conductors and 1 ground wire. I guess I am going to get #6 Copper THHN conductors, but I am unsure what size wire of ground to get? should the ground also be THHN? Or can they be bare (Just like the picture)?
 
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Old 06-04-09, 12:42 AM
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For linking this type of picture it is not a issue here.

Now for your orinial pullout disconnect switch now that is very serious issue that need to be replace.

Do you have any slack inside the buliding where is the SE cable go out to the pullout disconnection switch ?

If so you can able pull out few inches and cut off the bad part and make a new connection with new pullout disconnect switch { make sure you get a 60 amp verison due both 30 and 60 amp are pretty close the same size so watchout on the rating }

For grounding conductor you can have it either green or bare it don't matter for Air conding unit.

THE AC REPAIRMAN RECOMMENDED:
60amp double breaker (leave as is)
New 6-2 Cu Romex
New 60amp fusible disconnect box
New time-delay fuses
and quoted an arm and a leg for his services
Want my option ? C'est dingue et fini y tuent fondé.
{ it is nuts and overkill for that set up }

The 8-2 NM or SE will work just fine for this useage { there is a nice loophole on the NEC code realted to this so take a advange of it }

Merci,Marc
 
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Old 06-04-09, 07:31 AM
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Originally Posted by Penguin9 View Post
I don't know if linking pictures is considered breaking the rules, if I have broken the rules, I can promptly remove this link. I felt this picture would help visualize things a little better.
Not at all -- pictures are welcome. It really helps us to see the problem, especially in the case where we can notice something a layman might not have even thought to describe.

I guess I am going to get #6 Copper THHN conductors, but I am unsure what size wire of ground to get? should the ground also be THHN? Or can they be bare (Just like the picture)?
It should be #10 to match with #6 hots (or #8 hots). Green or bare is okay.

You actually have enough good wire in that box that you might be able to make it without replacing any. You only need to "stretch" an inch or two which can usually be done in an unfinished basement. Just loosen up the wire staples and see if you can get a little bit.

Same goes for the A/C side -- there's often a little bit of extra wire or the conduit is a little long and could be trimmed down a couple inches.

I'd even consider using butt splices to extend what you have a couple inches rather than repull that whole cable or put a junction box in the basement.
 
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Old 06-04-09, 07:01 PM
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Originally Posted by Penguin9 View Post
Nap and Ibpooks, you are both correct: I found the wires that connected to the AC terminal were trimmed down to 3 strands as opposed to the normal 6/7 required to make the connection.
If the #8 (or 6) did not fit the terminals of the disconnect I would suspect the existing disconnect is rated for only 30 amps. If it was a 60 amp disconnect, the lugs would plenty large enough to fit the #6 wire under.

I agree with all the others posts.
 
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Old 07-01-09, 09:36 AM
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Smile Same AC, different problem

This is really excellent information. Exactly what I was looking for.

I have the almost the exact same model (10ACC-060-230-02), but a different problem. Mine was installed with 10 gauge wire and a 30 amp circuit breaker. It tripps the breaker a couple of times each summer, but I never bothered to get it checked out.

Now I see that it has an Min Ckt Ampacity of 35.2. I plan to upgrade to 8 gauge wire with a 40 amp circuit breaker. It also does not have a ground wire. I will be adding one.

I would be happy to hear any comments/suggestions.

Thanks.
 

Last edited by klisjt; 07-01-09 at 12:12 PM. Reason: corrected model number
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Old 07-01-09, 12:19 PM
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If the nameplate of the A/C has a minimum circuit ampacity of 35.2 your A/C is fed with a too small feeder. This should be changed ASAP before it causes any damage to your A/C.

BTW - You should really have started a new thread rather then jumping into this one.
 
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Old 07-01-09, 01:48 PM
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klisjt- read the nameplate on your unit again. Whatever is says for maximum size HACR breaker, put that in. A 40 amp breaker will be too small for your 5 ton unit.
 
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Old 07-02-09, 02:51 PM
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First, very sorry for hijacking this thread. I was just trying be benefit from this discussion, because it was so closely related to my question.

Second, Thank you very much for the fast reply!

I will go with #8 wire (green #10 for the ground) and a 60 Amp breaker.

Thanks!
 
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Old 07-06-09, 08:58 AM
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Hope you check back but #8 is not large enough for 60 amps! You must use #6. However your #10 ground is ok.
 
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Old 07-06-09, 01:47 PM
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Originally Posted by Tolyn Ironhand View Post
Hope you check back but #8 is not large enough for 60 amps! You must use #6. However your #10 ground is ok.
Tolyn, If he runs #6 in romex to his box I beleive the new rating on this is now only 55 amps.
Jim
 
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Old 07-06-09, 01:55 PM
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Originally Posted by Penguin9 View Post
Nap and Ibpooks, you are both correct: I found the wires that connected to the AC terminal were trimmed down to 3 strands as opposed to the normal 6/7 required to make the connection.

All the charring occurred at the disconnect box, where the pullout disconnect was melted shut (we pulled the switch out and broke the inner cover), and the wires connected at the disconnect terminals were charred, with some light green deposit. This is what it looks like:


I don't know if linking pictures is considered breaking the rules, if I have broken the rules, I can promptly remove this link. I felt this picture would help visualize things a little better.

Pcboss, it does say "Max Fuse Or Circuit Breaker"; and per Nap and Ibpook's recommendation, looks like fuses do seem unnecessary.

QUESTION
For the connection from the new disconnect box to the AC unit, I understand I will need 2 conductors and 1 ground wire. I guess I am going to get #6 Copper THHN conductors, but I am unsure what size wire of ground to get? should the ground also be THHN? Or can they be bare (Just like the picture)?
I beleive your wires weren't tight at all. If you look at the lugs it looks like the wires weren't spread out at the bottom of the lugs making me think they weren't tight. I would install a new disconnect and if you have enough wire after cutting back the burnt area I would use it. Make sure your lugs are tight. After tightening them wriggle each wire near the lug and re-tighten again. If you're not sure run the 6-2 with ground to your disconnect. Make sure you also run #6 to your A/C from disconnect with a #10 for ground.
JimBeer 4U2
 
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Old 07-06-09, 02:10 PM
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Originally Posted by rukkus11 View Post
Tolyn, If he runs #6 in romex to his box I beleive the new rating on this is now only 55 amps.
Jim
You are correct. Romex is only rated at 55 amps under the 60 degree. But, since there is no 55 amp breaker 240.6(A)(2005) you are allowed to go to the next size breaker up which is 60 amps. 240.4(B)(2005) You can do this up to 800 amps. Over 800 amps you must drop down to the next lower breaker.
 
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